共查询到20条相似文献,搜索用时 31 毫秒
1.
D. V. Gorozhanin I. A. Dobranos B. I. Ivanov 《Radiophysics and Quantum Electronics》1992,35(3-4):222-229
Electron-beam interaction with an H-type resonator was used to study the anomalous Doppler effect at the electron cyclotron frequency with excitation in an electron beam of slow cyclotron waves, the anomalous Doppler effect at the plasma frequency with excitation of slow plasma waves, the energy relations for slow plasma waves, and the effect of reflected electrons and cyclotron absorption on the development of instabilities.Khar'kov Physicotechnical Institute, Academy of Sciences of Ukraine. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 35, Nos. 3, 4, pp. 334–346, March–April, 1992. 相似文献
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The dispersion properties of slow electromagnetic surface waves propagating across a constant external magnetic field and
along a plane plasma-metal interface at harmonics of the ion cyclotron frequency are studied. The motion of the plasma particles
is described by a Vlasov-Boltzmann kinetic equation. The effects of the plasma size, the dielectric permittivity of the transition
region between the plasma and metal, and the magnitude of the constant external magnetic field on the dispersion characteristics
of ion surface cyclotron waves are studied.
Zh. Tekh. Fiz. 69, 83–89 (October 1999) 相似文献
4.
Analysing the general dispersion relation numerically, the unstable regions of the relativistic electron-beam plasma system were determined. The external parameters were varied to ensure more effective instability excitations. The full charge and current compensation presumptions lead to new synchronism predictions. The return current's slow space charge wave and return current's slow cyclotron wave are synchronous with the plasma ion wave. 相似文献
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Sun-Kook Kim Jeong-Sik Choi Duk-In Choi 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1989,17(4):576-582
The general dispersion relation is derived for the fundamental transverse magnetic modes driven by a cold relativistic electron beam in a dielectric-loaded cylindrical waveguide using the fluid Maxwell equations. It is then reduced to the algebraic equation for the space charge and cyclotron modes using a tenuous beam approximation. Solutions of the resulting equation are obtained by varying several parameters, such as the external magnetic field the dielectric constant and the thickness of the dielectric material. It is shown that the growth rate of the slow cyclotron instability is greatly increased for the region of B o≲1000 G to the extent that it becomes comparable to the growth rate of a slow space-charge instability. In this region the magnetic-field effect on the slow space-charge mode is shown to increase the growth rate by up to 10%. In the limit of the critical external magnetic field defined as the field below which no beam equilibrium exists, it is found that two slow modes of cyclotron and space-charge modes become degenerate with a finite value of growth rate 相似文献
6.
Pant K.K. Tripathi V.K. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1994,22(3):217-223
The introduction of a strongly magnetized plasma in the inner region of a free electron laser opens up the possibility of generating coherent radiation in the slow whistler mode using mildly relativistic electron beams. The frequency of emission, however, is limited to below the electron cyclotron frequency. The efficiency of the device can be enhanced by tapering the guide magnetic field 相似文献
7.
A. V. Vodopyanov S. V. Golubev A. G. Demekhov V. G. Zorin D. A. Mansfeld S. V. Razin A. G. Shalashov 《Journal of Experimental and Theoretical Physics》2007,104(2):296-306
We have detected and investigated quasi-periodic series of pulsed energetic electron precipitations in the decaying plasma of a pulsed ECR discharge in a mirror axisymmetric magnetic trap. The observed particle ejections from the trap are interpreted as the result of resonant interaction between energetic electrons and a slow extraordinary wave propagating in the rarefied plasma across the external magnetic field. We have been able to explain the generation mechanism of the sequences of pulsed precipitations at the nonlinear instability growth phase in terms of a cyclotron maser model in which the instability threshold is exceeded through a reduction in electromagnetic energy losses characteristic of the plasma decay. 相似文献
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Based on a numerical analysis of the dispersion relation for a hot magnetoplasma, we study the spectra of weakly damped high-frequency
waves propagating in such a plasma in the case where the electron cyclotron frequency is higher than or equal to the plasma
frequency. It is shown that with increasing magnetic field, the branches of the ordinary and slow extraordinary waves approach
each other and become almost identical in wide ranges of frequencies and angles. A branch of waves with anomalous dispersion
can appear if the angles between the wave vector and the magnetic field are close to 90°.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 51, No. 2, pp. 136–141, February 2008. 相似文献
11.
M. J. Kurian S. Jyothi S. K. Leju Molly Isaac Chandu Venugopal G. Renuka 《Pramana》2009,73(6):1111-1122
We have studied the stability of the electrostatic ion cyclotron wave in a plasma consisting of isotropic hydrogen ions (H+) and temperature-anisotropic positively (O+) and negatively (O−) charged oxygen ions, with the electrons drifting parallel to the magnetic field. Analytical expressions have been derived
for the frequency and growth/damping rate of ion cyclotron waves around the first harmonic of both hydrogen and oxygen ion
gyrofrequencies. We find that the frequencies and growth/damping rates are dependent on the densities and temperatures of
all species of ions. A detailed numerical study, for parameters relevant to comet Halley, shows that the growth rate is dependent
on the magnitude of the frequency. The ion cyclotron waves are driven by the electron drift parallel to the magnetic field;
the temperature anisotropy of the oxygen ions only slightly enhance the growth rates for small values of temperature anisotropies.
A simple explanation, in terms of wave exponentiation times, is offered for the absence of electrostatic ion cyclotron waves
in the multi-ion plasma of comet Halley. 相似文献
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This paper presents an investigation of the resonant excitation of the electrostatic ion cyclotron wave at the difference frequency of two microwave beams propagating in a magnetoactive solid state plasma, viz. n InSb. The resonant excitation of the electrostatic ion cyclotron wave occurs when the difference frequency of the two microwave beams and the difference of their propagation vectors satisfy the dispersion relation corresponding to the electrostatic ion cyclotron wave. For typical plasma parameters of n InSb and microwave beams of power densities 1 MW cm?2, the power density of the excited ion cyclotron wave is 0.40 kW cm?2 when external magnetic field is . The power density of the excited ion cyclotron wave increases with the magnetic field. This study may provide new means for the characterisation and diagnostic of semiconductors. 相似文献
13.
On the basis of numerical solution of the dispersion equation, we obtain the spectra of weakly damped high-frequency waves
in a hot magnetized plasma for the case where the electron cyclotron frequency ωHe
is below the plasma frequency ωpe. It is shown that the longitudinal wave propagating at an angle to the magnetic field evolves into the slow extraordinary
wave for the refractive index n ≤ 1. For n ≫ 1, the longitudinal-wave frequency increases with the refractive index, and the
wave evolves into the wave with anomalous dispersion if the angle θ between the wave vector and the magnetic field is close
to 90°. In the same range of θ angles, Bernstein modes appear in the spectrum of plasma eigenmode oscillations.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 3, pp. 258–266, March 2006. 相似文献
14.
《Waves in Random and Complex Media》2013,23(2):114-127
Abstract The excitation of surface plasma waves due to the interaction of an elliptical relativistic density modulated electron beam with the magnetized dusty plasma column with elliptical cross-section has been studied. The dispersion relation of surface plasma waves has been retrieved from the derived dispersion relation by considering that the beam is absent and there is no dust in the plasma elliptical cylinder. It is shown that the Cherenkov and fast cyclotron interactions appear between the beam and eigen-modes of plasma column. The growth rate of the instability increases with the beam density and modulation index as one-third power of the beam density in Cherenkov interaction and is proportional to the square root of beam density in fast cyclotron interaction. The numerical results and graphs are presented, too. 相似文献
15.
E. G. Alexov 《等离子体物理论文集》1995,35(1):23-32
Backward waves in waveguides completely filled with magnetoactive plasma (gaseous or semiconductor plasma) have been investigated numerically. It is shown that two types of backward waves exist in such waveguides: cyclotron backward waves and waveguide HE-modes. While the cyclotron modes are backward waves at arbitrary system parameters (plasma density, magnetic field and waveguide radius), the waveguide backward waves appear only at certain values of there parameters. In addition the cyclotron backward waves can propagate at arbitrary wave-number kz and at arbitrary phase velocity. The backward waveguide modes exist only at limited values of kz and of phase velocities. 相似文献
16.
Tuning the flow of light by external fields is a challenging task for scientific studies and optical applications, but it is important in many applications such as switches, modulators, and slow wave structures. Here, new results are presented which demonstrate that this effectively can be achieved by external magnetic fields in one-dimensional photonic crystals made from semiconducting material. The advantage of using semiconducting material is the magnetic-field dependent dielectric function of the free charge carriers particularly where the magnetic field causes large and strongly varying contributions – near the plasma frequency and the cyclotron resonance frequency. The results of simulations on the basis of a multiple scattering method at infrared and microwave frequencies and of experiments on Indium Antimonide in the latter frequency regime confirm the tunability up to the extreme case from full transparency to opaqueness and vice versa. 相似文献
17.
A compact 14.5GHz electron cyclotron resonance (ECR) ion source for the production of slow, multiply charged ions has been constructed,with the plasma-confining magnetic field produced exclusively by permanent magnets.Microwave power of up to 175W in the frequency range from 12.75 to 14.SGHz is transmitted from ground potential via a PTFE window into the water-cooled plasma chamber which can be equipped with an aluminum liner.The waveguide coupling system serves also as biased electrode,and two remotely-controlled gas inlet valves connected via an insulating break permit plasma operation in the gas- mixing mode.A triode extraction system sustains ion acceleration voltages between 1kV and 10kV.The ECR ion source is fully computer-controlled and can be remotely operated from any desired location via Ethernet. 相似文献
18.
A technique is proposed for estimating parameters of the plasma produced by a source based on the electron cyclotron resonance. The analysis is made for the ion cyclotron resonance (ICR) facility designed for separating calcium isotopes. It is assumed that the resonance condition for an extraordinary wave is fulfilled for electrons moving towards the wave. The plasma optical thickness, the transverse energy of resonance electrons, and its dependence on the longitudinal velocity are determined. The charged particle density in the plasma flow is estimated in terms of the balance of the electrons generated as a result of vapor ionization in the discharge zone and the electron losses due to longitudinal ambipolar diffusion. 相似文献
19.
The properties of plasma and magnetoplasma excitations in free-hanging graphene have been studied for the first time by Raman scattering. In addition to single-particle excitations associated with transitions between empty Landau levels of electrons and holes, collective plasma and magnetoplasma excitations in the system of electrons (and holes) of various densities have been discovered for the first time. Hybridization of plasma and cyclotron modes corresponding to the Kohn law has been shown to occur in the limit of high filling factors, which allows measuring directly the plasma and cyclotron energies. The dependence of the electron and hole velocities on their density has been investigated via the magnetic-field dependence of the cyclotron energy in free-hanging graphene. The effect of strong renormalization of the electron and hole dispersion relations seen as an increase in the velocity (by 40–50%) with a decrease in the charge-carrier density to 1011 cm–2 has been discovered. The charge-carrier density dependences of the widths of magnetoplasma resonances in free-hanging graphene and graphene lying on a silicon dioxide surface have been measured and shown to be at least 3.5 and 14.8 meV, respectively. 相似文献
20.
In this paper we consider the plasma maser theory of whistler waves in the presence of ion cyclotron waves in a magnetized plasma. In a plasma with low frequency ion cyclotron turbulence and a high frequency test whistler wave, growth of the whistler wave takes place because of the turbulent bremsstrahlung interaction between the resonant electrons and the modulated electric fields. The growth rate of the whistler wave is calculated and the results discussed. 相似文献